This research project will study the synthesis and secretion of human chorionic gonadotropin. This hormone is a tissue specific protein hormone made at the beginning of pregnancy. It is used as a marker to detect pregnancy, and must be circulating in the mother's blood stream to maintain the fetus for the first weeks of growth. The protein is made as separate alpha and beta subunits which are glycosylated then joined together for secretion. This research will use a cell bank of cultured cells to study the mechanisms and controls involved in this process of synthesis and secretion. The cells lines are derived from a human placental tumor established as cultured cells, and other cells containing portions of the information for hormone synthesis. The intracellular forms of the hormone can be labeled with isotopes, isolated with specific antibodies, and analyzed by gel electrophoresis. This is done to trace the formation of the protein and its modification with carbohydrate to become a mature biologically active protein. Placental cells and tumor cells secrete many forms of hCG but their regulation is not completely understood. Studies of several cells lines will aid in understanding the sizes of subunits involved, size variation is due to protein and how much is due to carbohydrates. Some cells produce only one subunit and the regulation of its synthesis and secretion is also important in understanding gene activation. The maintenance of pregnancy requires that the hormone be synthesized properly and carbohydrate addition is essential for biological activity. The regulation of secreted levels is also essential. These cells can be used as a model system for the other subunit protein hormones TSH, LH, and FSH. It will also give information on protein hormones such as insulin that are synthesized and modified before they are secreted.